Spray gun activation mechanism



E. O. NORRIS SPRAY GUN ACTIVATION MECHANISM Aug. 13, 1968 Original Filed Jan. 27, 1964 3 Sheets-Sheet 1 INVENTOR EOWAQD O NOR/Q/S I BY 1/ A! ATTO RNE 1968 E0. NORRIS 3,396,911

SPRAY GUN ACTIVATION MECHANISM Original Filed Jan. 27, 1964 3 Sheets-Sheet 2 I /3 /09 45 m I09 w 75 I I 9. I :2 70 75 .96 I 74 Y L; zl Z4 HH "2 2 1 23 i'l'ii ii T 74 99 lo, 99 IT?A""ANM it I /08 HO 1 unuifi fl 98 T I /0 //0 l KJJI'I 4 //0 x 96 98 m6 8- 1968 E. o. NORRIS 3,396,911

SPRAY GUN ACTIVATION MECHANISM Original Filed Jan. 27, 1964 3 s 5 I IH l W II 50 INVENTOR EDWARD 0 N0? 5 ATTOR United States Patent 3,396,911 SPRAY GUN ACTIVATION MECHANISM Edward 0. Norris, 9 Ledgemoor Lane, Westport, Conn. 06880 Original application Jan. 27, 1964, Ser. No. 340,466, now Patent No. 3,344,992, dated Oct. 4, 1967. Divided and this application Sept. 29, 1967, Ser. No. 671,706

11 Claims. (Cl. 239290) ABSTRACT OF THE DISCLOSURE The invention relates to an air-liquid type of spray gun having supplementary air jets impinging on the spray cone soon after it emerges from the spray nozzle. The supplementary air jets serve the function of shaping the spray cone to a predetermined desired form and of reducing the high spray particle velocity, which is necessary for good atomization, to a level suitable for good deposition, especially by electrostatic means. A two-stage, single trigger control element is provided for activating the spray gun. In one position of the trigger, the gun emits a low velocity fan shaped spray, desirable for coating most surfaces. In another position of the trigger, the spray shape is changed to concentrated spot, and the spray is applied at a higher velocity, which is desirable to ena-ble the spray to be directed into relatively inaccessible places. A mechanism for reducing the flow of spray material when the flow of gas to the supplementary jets is stopped is also disclosed.

Reference to related applications This application is a division of my copending application Ser. No. 340,466, now US. Patent 3,344,992, granted Oct. 4, 1967.

Snmmary and background of the invention This invention relates generally to air-liquid atomizing spray guns of the type wherein supplementary air jets are provided to impinge air streams onto the cone of atomized spray material. A primary purpose of such impingement is to shape the spray cone to a specific form desired for a specific spray painting application, such as a flat spray for covering relatively large articles. Another important reason for providing these supplementary air jets is to reduce the spray particle velocity, which desirably is very high at the nozzle, for good atomization, but is desirably quite low for good deposition on the sprayed surface, especially if electrostatic deposition means are used. A particularly advantageous arrangement for effecting particle velocity reduction and spray shaping is obtained by providing rearwardly directed air jets, in the manner described in my previously referred to U. S. Patent 3,- 344,992.

The present invention is primarily concerned with providing a novel spray gun mechanism, provided with a single two-stage trigger control, which includes means for varying the velocity of the supplementary air jets and thereby varying the velocity of the atomized particles as well as the shape of the spray pattern. Such variation of velocities is desirable in spray painting production lines since it is occasionally necessary to paint recessed areas of the article being painted. By controllably reducing the velocity of supplementary air jets, the velocity of the spray particles is caused to increase, and the fiat spray pattern tends to return to its initial cone shape. This results in a spray pattern that is more concentrated and has a greater reach, thereby permitting the same gun to be used to cover large, broad areas with a wide fan, using using low velocity, electrostatic deposition, and also to reach small recessed areas as well, with a concentrated, high velocity spray.

The invention also provides an advantageous control arrangement for the correlation of spray volume with spray particle velocity. This is accomplished by providing means for reducing the amount of spray material flowing to the spray nozzles as the air supply to the supplementary air jets is being reduced. Such correlation of spray particle velocity and volume is desirable in some cases, in that it minimizes the possibility of paint build up in recessed areas.

More specifically, the present invention provides a spray gun flow control mechanism, activated by a one-hand operated two-stage trigger member, that regulates both the flow of spray material to the spray nozzle and gas to the supplementary jets. A provision for correlating spray particle velocity and volume can also be included in this control mechanism. In accordance with the invention, a two-stage trigger mechanism is provided for controlling both the flow of spray material to the spray nozzle and air to the supplementary jets. The two stages of the trigger mechanism are discernible by a difference in the force' required to displace the trigger through each stage. In a preferred embodiment of the invention, this difference in force results from the engagement of a shoulder on the spray gun by a spring mounted element, when the trigger has been displaced through its first stage. As the trigger is displaced past this point of engagement, i.e., into the second stage, the spring mounted element is compressed, thereby requiring a greater force to displace the trigger into the second stage. This difference in force required for trigger displacement readily indicates to the operator, without visual reference, that the end of the first stage has been reached and that further trigger displacement will commence the second stage control functions.

Most advantageously, and in accordance with the specific embodiment to be described in detail, displacement of the two-stage trigger control through the first stage fully opens the spray nozzle valve, resulting in a maximum flow of spray material. At this time, the atomizing gas flow and supplementary jets gas flow also is at its maximum. When the second stage of the trigger mechanism is reached, the conduit supplying air to the supplementary jets is partly or entirely closed. In the specific embodiment described herein, engagement of the second trigger stage also closes the spray material supply valve to some degree, thereby providing less spray material as the velocity of the spray particles is increased in response to the closing of the supplementary air jet supply conduit. This has the eifect of avoiding excessive paint build up in the recessed areas being painted by the high velocity spray.

By providing for both control function stages to be performed with a continuous motion of a single control trigger element, it is possible for an operator to instantly change from one control stage to the other as he works without interruption upon the surface of an article being painted. The arrangement of the invention enables the operator to use one hand for spray control and the other hand to support and steady the spray gun, and the manipulation of the control trigger may be performed entirely by manual feel, so that the operator need not divert his attention from the work.

Brief description of the drawing For a further understanding of the invention reference of the gun which when joined to FIG. 1 along the line a-a illustrates the complete gun;

FIG. 2 is a detail illustrating one form of supplementary air jet;

FIGS. 3, 4 and are cross-sectional views, taken generally on lines 3-3, 4-4 and 5--5 of FIG. 1;

FIG. 6 is a side elevation of a portion of the gun of FIG. 1;

FIG. 7 is a transverse section taken on line 7-7 of FIG. 6;

FIG. 8 is a transverse section taken on line 8--8 of FIG. 1 looking in the direction of the arrows;

FIG. 9 is a transverse section taken on line 99 of FIG. 6;

FIG. 10 is an axial section taken on line 1010 of FIG. 9;

FIG. 11 is a detail of a cam and cam follower control mechanism incorporated in the apparatus of the invention;

FIG. 12 is a transverse section through the spray taken on line 12-12 of FIG. 1; showing an elliptical spray pattern;

FIG. 13 is a view similar to FIG. 12, illustrating a spray pattern of substantially circular form;

FIG. 14 is a detail view, partly in section and on a reduced scale, illustrating a further embodiment of a supplementary air jet; and

FIG. 15 is a section taken on line 15-15 of FIG. 14.

Description of preferred embodiments Referring to the drawings more in detail, the spray gun is shown as comprising a spray gun barrel 13, formed of plastic material, and having a longitudinal bore 14 constituting a passage for paint or other material to be sprayed. This barrel also is provided with a passage 15 for conducting air to the nozzle, and a passage 16 for conducting air to supplementary jets to be described. The front end of the barrel 13 has a central bore 19, registering with the longitudinal passage 14, into which a tube 20 is threaded. The forward end of the tube 20 is threaded to receive a clamping nut 31, which in turn secures tapered nozzle member 32.

A hollow annular horn ring 21, having an annular pas sage 22 therein, is disposedagainst the end surface 23 of the barrel and is secured by a ring nut 24. The annular passage 22 communicates with the air passage 16 in the barrel. A pair of hollow air jet tubes25, in the form of a J, are attached to the ring 21, in communication with the annular passage 22. The jet tubes 25 taper in size toward their free ends, which are bent inwardly to direct the air therefrom at an acute angle toward a predetermined zone 26 in the spray pattern 27, to be described. The jet tubes 25 and the ring 21 may be made of metal and coated with an insulating material- 28, or they may be made entirely of plastic.

A valve tube 33, provided with a flange 34, is seated within the tube 20 and is aligned therewith by fins to provide an air space 36 therebetween. The fins 35 terminate forwardly of the flange 34. to provide an annular air passage 37 between the tubes 20 and 33.

In the illustrated form of the invention, the, barrel 13 has an annular passage 38 in its forward end communicating with the air passage 15. The tube 20 is formed with openings 40, through which air is supplied from the annular passage 38 to theannular nozzle passage 37. The valve tube 33 advantageously is formed with an external annular rib 39, registering with the discharge end of the tapered nozzle member 32, to provide a concentric annular discharge orifice for air supplied to the passage 37.

As shown in FIG. 1, the valve tube 33 terminates in a conical valve seat 41 against which a valve head 42 seats. A valve stem 117 extends from the head 42 to a connecting sleeve 47, and a non-conducting rod 44 extends from the sleeve 47, through a spring pressed stuffing gland 45, and projects from the rear end of the barrel.

Suitable pins connect the valve stem 117 to the sleeve 47, and also the sleeve to the nonconducting rod 44. A compression spring 46 surrounds the valve stem and extends between the valve tube flange 34 and the sleeve 47 to bias the valve to its closed position.

Handle members 50 for the gun are formed by sections 51, 52, which are clamped around the rear portion of the barrel 13 and are formed with flanges 53 which are secured by bolts 54. A paint tube 55 extends through the gripping portion 52 of the handle and is threaded into a bore 56 in the barrel 13 which communicates with the axial passage 14. An air tube 58 also extends through the handle portion 52 and is threaded into a bore 59 in the barrel 13 which communicates with the passage 15.

A high voltage wire 60 is connected to a spring 61 which is secured in the air tube 58 and supports a resistor 62 centrally of the tube 58 to provide an annular passage for cooling air over the surface of the resistor. The resistor 62 is connected by a wire 63 which extends through the bore 59 and through an axial bore 65 in the gun barrel, to a washer 66 clamped between the tube 20 and a shoulder in the central bore 19, to provide an electrical connection to the nozzle and to the supplementary jets. The washer 66 also serves to seal the paint passage 14 from the air passage around the tube 20. The axial bore 65 is filled with a hardened sealing compound. A grounded sheath 67 is disposed around the lower portion of the air tube 58 and is connected to the handle 52 by a screw 68.

The passage 16, from which air is supplied to the supplementary jets, is connected by a transverse passage 70 (see FIGS. 6, 9 and 10) to a longitudinal passage 71 of larger diameter, which in turn is connected by a transverse passage 72 to the passage 15. A piston valve 73 slides in the passage 71 and is adapted to variably close the opening to the passage 72. The valve 73 is actuated by a stem 74 which projects through a packing gland 75 beyond the rear end of the barrel 13.

A single control trigger is pivoted on a pivot 81 supported in ears 82 on the handle portions 52, in a position to be gripped'by the operator. The trigger 80 carlies a cross arm 83 to which a bridge member 84 is pivoted and is adapted to be moved forwardly as the trigger is operated. A rotatable cam 85 is journalled between ears 86 from the handle portions 51 and has a depending arm 87 which is adjustably secured to the bridge member 84 by a screw 88 having a ball 89 and socket connection with the control arm '87 and adjustable by a screwdriver slot in the ball 89. A compression spring 90 is interposed between the bridge piece 84 and the arm 87, to normally maintain these elements in a fully separated condition.

A cam follower arm 91 is pivoted at 92 on the handle portions 51 and bears against a cam surface on the cam 85 (see FIG. 11). This cam surface includes a sharp rise 93 followed by a slowly receding surface 94 which surfaces are successively engaged by the cam follower arm 91 as the trigger is actuated to pivot the control arm 87 in a clockwise direction. An adjusting screw 96 is carried by the cam follower arm 91 in a position to engage and actuate the valve rod 44 for variably opening the paint supply valve. The arrangement is such that the paint valve is fully opened by a limited displacement of the trigger and is thereafter slowly closed as the trigger is further displaced in the same direction.

A setting spring 97 is interposed between the head of the adjusting screw 96 and the arm 91 for maintaining the adjustment of the screw 96.

A screw 98, in an arm 99 carried by the bridge piece 84, is positioned to engage and actuate the valve stem 74 for controlling the air supply to the supplementary jets 25. The piston valve 73 normally is held in open position by a spring 100, as reflected in FIG. 10. In accordance with the invention, the adjusting screw 98 is set to provide a predetermined clearance with the valve stem 74, such that the valve remains fully open when the trigger is displaced to an extent suflicient to fully open the paint valve 42. However, upon continued displacement of the trigger the screw 98 actuates the valve stem 74 to gradually close the air passage, so that the supply of air to the jets is reduced.

A tension spring 101 between an ear 102 on the bridge piece 84 and pivot pin 103 of the cam 85 biases the bridge member to its retracted position. A sliding pin 106, urged forwardly by a spring 107, is slidably held in the bridge piece 84 and held in an adjusted position by setting nuts 108.

The pin 106 is set to engage a shoulder surface 109 on one of the handle portions 51 when the trigger 80 is displaced to the extent required to fully open the paint supply valve. Displacement of the trigger to a greater extent requires the "application of a greater force than the first stage of the trigger displacemnet since spring 107 must be compressed. A two stage trigger mechanism is thereby provided for regulating the flow of paint and air to the supplementary jets and to indicate the fully open position of the paint valve. A screw 110, adjustably received in the bridge piece 84, provides a fixed stop to limit the movement of the trigger and the actuation of the valves at the end of the second stage of control trigger movement.

In FIG. 1 the supplementary jets are shown in the form of tubes secured to the ring 21. In FIG. 2 the jets are shown as integral with the ring 21 and are provided with separate end pieces 111 which may be removed for cleaning or for varying the orifice size.

In the embodiment of FIGS. 14 and 15 air jets 125 are mounted on U-shaped tubes 126 which are supported on the horn ring 21 at diametrically opposite points. In this way each support is located out of the direct path of the air ljet from the opposite nozzle so that build up of paint on these elements is avoided.

For manually opening the paint valve, as for clearing the nozzle, a bell crank lever 112 is pivoted to the handle portions 51 by a pin 113 and is formed with a horizontal leg 114 adapted to engage the cam follower arm 91 to force the same into fully open position, and with an upstanding arm 115 positioned for manual actuation. A suitable stop 116 limits hte movement of the lever 112.

In the operation of the gun, atomizing air is supplied from the tube 58 through the passage bore 59 and passage 15, annular passage 38, and through openings 40 in the tube 20 to the annular orifice 37 between the cap 32 and the tube 33 where it is discharged in a jet of cylindrical cross section. This air is supplied at all times while the spray gun is in operation.

Paint or other liquid to be sprayed is supplied from the tube 55 through passages 56 and 14, to the nozzle formed by the valve head 42 and its seat 41. This valve is normally closed but is opened for spraying when the trigger 80 is displaced through its first stage of movement to cause the sharp rise 93 of the cam 85 to engage and actuate the cam follower 91 and advance the valve 42 to an open position. The extent of opening of the paint valve is determined by the setting of the screws 89 and 96. At this point of trigger displacement the pin 106 engages the shoulder 109 indicating to the operator that the paint supply valve is in its fully open position. Since the operator can readily feel the engagement of the pin and shoulder, it is not necessary for him to take his eyes off of the workpiece he is coating.

The paint or other liquid thus discharged from the orifice around the valve 42 is immediately contacted by the air stream to form an atomized spray which first decreases in cross-section to a zone 26 of minimum crosssection and thereafter diverges in an expanding cone 27 of spray of substantially circular cross-section.

The spray particles in the main spray stream, as above described, are discharged with a substantial velocity toward a work surface, in order to achieve optimum atomization. These particles can be further directed forward and attracted to a work surface by an electrostatic charge,

4 which is supplied by the high voltage wire 60 through the resistor 62 and wire 63 to the metallic tube 20 through which the liquid passes.

In typical operation, the velocity of the spray particles is substantially reduced and the cross-sectional shape of the spray pattern is desirably modified by air streams 119 from the jets 25 which are directed to impinge on the spray cone in the zone 26 of minimum cross section and at the diametrically opposite points 120. The air supply to the jets passes from the tube 58 through passages 59 and 15 to the annular passage 22 in the ring 21, thence to the jet nozzles 25, from which it is discharged angularly inward toward the zone 26 and rearwardly of the direction of the stream of the spray particles. The air valve 73 is normally retracted from the passage 72 when the trigger is in full spray position so that maximum air pressure is supplied to the supplementary jets.

The air streams, from the supplementary jets, impinging on the spray cone at the zone 26, distort the cross section of the spray to an elongated ellipse, having reentrant sides at the points of impingement of the air jets, and causes the diverging spray cone to take the form of an elongated ellipse as shown in FIG. 12. This ellipse may be closed to a predetermined extent to form a fan shaped spray pattern, the extent of the spread of the fan being determined by the air pressure and the velocity of the air discharge from the jets 25.

The air from the jets 25 passes in a direction having a large axial component opposed to the advance of the spray particles. This component of the air stream serves to reduce the velocity of the spray particles to substantial extent, such that they are readily deflected by the electrostatic charge to the work surface. In this way maximum deposition efiiciency is obtained.

As previously mentioned, it is sometimes desirable during the operation of the spray gun, to increase the spray velocity, for example, in order to reach recessed parts. This is accomplished by displacing the trigger member beyond its first stage. This is done against the increased resistance of spring 107, which is being compressed, and therefore requires a greater force than that required to displace the trigger through its first stage. As the trigger is displaced through its second stage the screw 98 engages the valve stem 74 to progressively advance the piston valve 73 thereby restricting the air passage 72 and reducing the air flow to the supplementary air jets 25. As the air flow to the supplementary jets is decreased, the retarding effect of this air stream on the spray is decreased and the velocity of the spray particles in correspondingly increased. At the same time the distorting effect of the jet air stream on the spray pattern is reduced and the spray pattern is altered from the elliptical form shown in FIG. 12 to the circular form shown in FIG. 13. Hence the width of the spray fan is decreased as the velocity of the spray particles is increased.

In order to prevent excessive paint deposition in the narrowed spray pattern, which may result when the jet air streams are reduced, displacement of the trigger 80 through the second stage has the additional effect of further rotating cam 85, causing the inclined surface 94 to engage the cam follower 91 and slightly close the spray valve so as to decrease the amount of spray material supplied to the spray nozzle. In this way both the spray particle velocity and the spray volume can automatically be correlated.

The spray gun mechanism of the invention is particularly advantageous in that it permits the character of the spray pattern to be altered significantly through manual manipulation of a single control element, typicall and most advantageously a trigger type of control. By providing for a two stage control, which the operator may regulate by feel alone and with one hand only, the spray pattern to be applied may be readily varied in an advantageous manner during regular production. During normal operations, the spray gun is activated to. provide a wide, fiat fan of atomized spray material for maximum area coverage. However, to coat a deep recess, for example, it may be desirable to concentrate the spray pattern, and this may be accomplished by further continuous movement of the control trigger. Since the control requires only one hand, the operators other hand is always available to steady the gun, hold up the supply hoses, etc. Likewise, it is not necessary for the operator to remove his eyes from the work, because he can easily feel the important operating positions of the control trigger.

The two stage control is applicable to particular advantage in the illustrated spray gun, in which the principal spray pattern is of a convergent-divergent form and in which the supplementary jets are directed rearwardly, to have a significant retarding effect on the spray material. When the supplementary jets are shut off, the spray pattern forms a relatively narrow cone of generally circular cross section and the spray particle velocity is increased, for optimum penetration into small, recessed areas.

It should be understood, however, that the specific form of the invention herein illustrated and described is intended to be representative only, as certain changes may be made therein without departing from the clear teachings of the disclosure. Accordingly, reference should be made to the following appended claims in determining the full scope of the invention.

I claim:

1. In a spray gun of the type wherein supplementary gas jets are provided to intercept an atomized spray cone and wherein a hand operated control member is provided for controlling the flow of spray material to the spray nozzle the improvement which comprises:

(a) means mounting said control member to have two stages of control movement,

(b) main valve means being provided in said gun for controlling the flow of spray liquid,

(c) said main valve means being normally closed and being actuated to an open position by movement of the hand operated control member through its first stage of movement,

((1) supplementary valve means being provided in said gun for controlling the flow of gas to the supplementary jets,

(e) said supplementary valvemeans being open when said control member is moved through its first stage of movement and being actuated toward a closed position upon continued movement of the control member into its second stage.

2. The improved spray gun of claim 1, further characterized by:

(a) said hand operated control member comprising a rearwardly displaceable, two-stage trigger member, and

(b) sensing means being provided, whereby the stages of said two-stage trigger member are discernible by a change in the force required to displace the trigger member.

3. An activation mechanism for spray guns having supplementary gas jets intercepting an emitted spray cone comprising:

(a) a trigger member movably mounted on the spray (b) a bridge membermovably mounted on the spray (c) connecting means joining said bridge member to said trigger member,

(d) said connecting means causing forward translational motion of the bridge member in response to rearward movement of the trigger member,

(e) spray material valving means movably connected to said bridge member for controlling the flow of spray material to the spray nozzle,

-(f) said spray material valving means supplying a maximum flow of spray material in response to a predetermined partial rearward movement of said trigger member, and

(g) normally open supplementary jet valving means,

movably connected to said bridge member, for controlling the flow of gas to the supplementary jets,

(h) said supplementary jet valving means being activated toward a closed condition by rearward movement of said trigger member in excess of that required for maximum spray material flow.

4. The activation mechanism of claim 3 further including:

(a) sensing means associated with said trigger member for indicating said predetermined partial rearward movement thereof.

5. The activation mechanism of claim 4, further characterized by:

(a) said sensing means comprising an element yieldably mounted on said bridge member and engageable with an abutment surface to a change in force required to rearwardly move said trigger member.

6. The spray gun activation mechanism of claim 3,

wherein:

(a) said spray material valving means includes regulating means for slowly decreasing the flow of spray material in response to continued rearward movement of the trigger member in excess of said predetermined partial rearward movement.

7. A spray gun for the spray coating of liquid spray materials, comprising:

(a) a discharge nozzle for atomized spray material,

('b) supplementary gas jets for modifying the condition of the atomized spray,

(c) separate valve means for said spray material and said supplementary gas jets,

(d) a common manual control member for said separate valve means having a plurality of operative control stages,

(c) said control member in one control stage being operative to open both of said separate valve means, and being operative in another control stage to at least partially open the spray material valve means and at least partially close the valve means for the supplementary gas jets,

(f) whereby, in said one control stage of said member, a relatively flat spray fan is provided and, in the other control stage of said member, a relatively more circular spray pattern is provided.

8. The spray gun of claim 7, further characterized by:

(a) said manual control member comprising a trigger-like element,

(b) said one control stage comprising a first stage of rearward movement of said trigger-like element, and

(c) said other control stage comprising a further stage of continued rearward movement of said trigger-like element.

b 9. The spray gun of claim 7, further characterized (a) said supplementary gas jets being rearwardly and inwardly directed and being operative when actuated to flatten the shape of, and significantly retard the velocity of, the atomized spray material,

10. In combination with a spray gun of the type wherein the spray material and atomizing gas are supplied to the spray nozzle through independent passages and wherein the atomized spray cone is shaped or reduced in velocity shortly afterleaving the spray nozzle by impinging gas streams discharged from gas jets supplied through an impinging gas supply passage which is at least partially independent of the atomizing gas supply passage and wherein valving means are provided for selectively opening or closing the spray material supply conduit and wherein the valving means is opened by a predetermined displacement of a hand operated trigger member, the improvement which comprises:

9 10 (a) means mounting the hand operated trigger mem- (a) said sensing mechanism comprising a yielda'ble bet for displacement greater than the predetermined element engaged and displaced by said trigger memdisplacement necessary to open the spray materlal ber When said member is displaced beyond a predesupply passage,

(b) means providing a sensing mechanism in conjunc- 5 tion with the trigger mechanism to indicate said predetermined displacement of the trigger member, and

termined distance.

References Cited (c) a second valving means to control the impinging UNITED STATES PATENTS gas supply passage,

(d) said second valving means being activated by dis- 10 1326348 12/1919 Kelly 239415 placement of the trigger member in excess of said 1,480,260 1/1924 Haas 239-415 predetermined displacement necessary to open the ,19 ,356 2/1940 Fausek et al. 239-415 spray material supply passage.

11. The improved spray gun of claim 10, further char- EVERETT W. KIRBY, Primary Examiner. acterized by: 15 

